The present invention relates to a joint structure of a jointing portion between plate members constituting a duct used for air-conditioning or ventilating equipment as one of building equipment.
Traditional mode of ducts (see FIG. 19) have been conventionally used for air-conditioning or ventilating equipment for last 100 years or more. The present inventor provided a novel mode of duct as shown in FIGS. 17, 18, which can be assembled with a minimum of noise, delivered and stored with high efficiency, and hung through a simple operation and with high degree of freedom in terms of the position at which the duct is hung (Japanese Laid-Open Patent Publication No. Hei 10-47741).
Because of the features described above, the novel mode of duct shown in FIGS. 17, 18 has attracted the attention from the duct industries in the United States, European countries, and other countries, not to mention Japan.
However, the novel mode of duct can not be easily manufactured by a conventional duct forming machine or even by an improved version of the conventional duct forming machine because the structure of a joint portion of the novel mode of duct is more complicated than that of the conventional duct and new. That is, as shown in FIGS. 17, 18, a thin plate member is bent twice, and a portion of the bent plate member is required to be further bent. Thus, the influence of the distortion, etc. is complicated and large, making the sheet metal working more difficult as compared to the joint structure of the conventional duct. Consequently, the novel mode of duct is not something that anybody can fabricate easily even with a new forming machine incorporating the conventional sheet metal working technologies. That is, a desired shape may be obtained if a number of required conditions are all satisfied, however, the desired shape can be no longer formed if one of the required conditions changes because of, for example, a change in surface roughness of a forming roller with use.
The present invention has been developed under these circumstances, and an object thereof is to provide a joint structure of a duct formed easily and having the features of the novel duct described above.
To solve the above-described technical problem, according to the first invention, there is provided a joint structure of a duct in which a guide rail extends along a jointing line at which two plate members are substantially orthogonal to each other in cross section in the vicinity of the jointing line, the joint structure of the duct characterized in that:
an end portion of the one of the two plate members is bent to form an angle of 90 degrees or more;
a U-shaped groove (not only an exactly U-shaped groove but also a groove opened in one direction, such as an reversed-xcexa9or inverted-V shaped groove) is formed at an end portion of the other plate member such that at least a portion in the vicinity of an opening portion of the groove is adapted to the bending angle of the bent end portion of the one plate member so as to accommodate a tip end portion of the bent portion of the one plate member;
the guide rail is formed by protruding at least a bottom portion of the U-shaped groove of the other plate member from an outer face located on a base end side of a portion where the U-shaped groove is formed and constituting one of walls of the duct.
Therefore, according to the joint structure so constituted, the number of portions to be bent during forming can be reduced to its half as compared to the conventional new joint structure of the duct, and a forming step in which a portion of a bent plate member is further bent can be eliminated, thereby enabling simple and stable fabrication.
Furthermore, the joint structure so constituted can have the feature of the joint structure of the conventional new duct that it can be assembled with a minimum of noise, delivered and stored with high efficiency, and hung through a simple operation and with high degree of freedom in terms of the position at which the duct is hung.
Furthermore, in the joint structure of the duct, the extension of a U-shaped groove obliquely and linearly with respect to an outer face located on a base end side thereof and constituting one of the wall faces of the duct can offer a very simple and preferred embodiment.
Even furthermore, in the joint structure of the duct, a U-shaped groove can be constituted such that a tip end portion of the bent portion of the one plate member is accommodated in a portion in the vicinity of an opening portion thereof, and a bottom portion of the U-shaped groove protrudes with respect to an outer face located on the base end side and constituting one of the wall faces of the duct.